This planning grant will: (1) Support a collaboration among experts in genetics, toxicology, andrology, reproductive endocrinology, biostatistics, high throughput genotyping, ethics and epidemiology to design studies of gene-environment interaction in a large, existing cohort (20,000 pregnancies in The Child Health and Development Studies, CHDS). CHDS families have been followed for a variety of outcomes, for more than 40 years. Biological samples for both parents are available. (2) Determine the feasibility of fully characterizing single nucleotide polymorphisms (SNPs) in CHDS families using currently available gene chips with densities of 1,400 SNPs. (3) Plan a research/industry Consortium to fund genome characterization in the CHDS using higher density chips as they become available and economic. (4) Design and implement human subjects protections and informed consent. The use of CHDS allows: (1) measures of endogenous prenatal exposures, including reproductive hormones, in stored biological samples; (2) direct measures of prenatal environmental exposures in stored samples; (3) enrollment of subjects in new data collections to measure later life exposures and outcomes; (4) investigation of multiple, related health outcomes over the life span using existing data, thereby avoiding a 40-year waiting period for a new study; (5) study health effects for high levels of prenatal exposure to endocrine disrupting chemicals, in addition to pharmaceuticals, tobacco, caffeine and alcohol; (6) study haplotypes and other genetic designs made possible by having samples from both parents. This planning grant will result in: (1) R01 applications on gene-environment interaction in fetal life and later, and (2) pilot data that will establish feasibility in order to generate funding from multiple sources to create a research community/industry Consortium. The Consortium will aim to complete a library of SNPs for the CHDS population at low cost using state-of-the-art technology. The SNP library will be a resource of unparalleled power that will be used in conjunction with emerging identification of relevant polymorphisms by the NIEHS Environmental Genome Project to study gene-environment interactions.